Load snubber for a crane



June 4, 1968 K. E. REISCHL LOAD SNUBBER FOR A CRANE 8 m a 05+ 1. m 3 2 3 a S 3 .r a m Q 2 m2 T s 2" 1' M0 :2 5 I a k\ J A I I I 5 a w m @WEM- r].

Filed April 13, 1967 INVENTOR KARL E.RE|SCHL avmz/z ATTORNEY June 4, 1968 K. E. REISCHL LOAD SNUBBER FOR A CRANE Sheets-Sheet 2 Filed April 15, 1967 INVENTOR KARL E. REISCHL B %-1/ AT TORNEY June 4, 1968 K. E. REISCHL LOAD SNUBBER FOR A CRANE 5 Sheets-Sheet 5 Filed April 13, 1967 INVENTOR KARL. E. REQSCHL BQZZTQW ATTORNEY United States Patent 3,386,592 LOAD SNUBBER FOR A CRANE Karl E. Reischl, South Milwaukee, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Win, a corporation of Delaware Filed Apr. 13, 1967, Ser. No. 630,681 7 Claims. (Cl. 212--1) ABSTRACT OF THE DISCLOSURE Each of three embodiments employs a brake drum in two segments mounted on the end of a jib with a hoist cable passing between them. A brake shoe having two resiliently mounted brake surfaces is mounted on the load to engage the drum segments. In the first embodiment, an eye is formed between the brake surfaces to be engaged by a conventional book. In the other two embodiments, a tubular socket is mounted on the load to receive a symmetrical hook, and the brake surfaces are mounted on the socket.

Background of the invention The present invention falls in the general category of devices for stabilizing and controlling a load suspended from a hoist cable of a crane. The load on the end of a hoist cable is virtually an ideal pendulum, and the problem of controlling the load, particularly when the crane is moving can be very serious. As the equipment with which cranes are used becomes more sophisticated, the problemof controlling a load with great precision looms large in importance.

The obvious expedients for controlling a load on the end of la hoist line would be some form of tag-line or guideline, but in any situation these are inefficient, ineffective and impractical. In one attempt to solve this problem, a pneumatically operated clamping means was mounted at the end of an articulated jib suspended from a broom, and the load was drawn up to the end of the jib where the pneumatic clamping means could engage the shank of the hoist line hook and attempt to stabilize it, but this proved unsatisfactory. In connection with a boom for controlling a sphere containing sonar equipment being towed by a ship, U.S. Patent No. 2,780,196, shows the attachment of a hollow cone on the end of the boom with the tow chain passing through the apex of the cone, so that the sphere containing the sonar equipment could be clamped into the cone to stow it when not in use. However effective that device may be for such sonar equipment, it fails to satisfy the need of crane applications. The present invention provides a solution capable of general application for use with cranes.

Summary of the invention The present invention relates to a load snubber on the end of a boom member on a crane, and the snubber of the present invention includes a pair of mating arcuate braking surfaces at least one of which is mounted on the end of a boom member, and the other is positioned between the first braking surface and a load, so that by hoisting the load against the end of the boom memher the braking surfaces are forced into frictional engagement to thereby stabilize the load on the end of the boom member.

It is a primary object of the present invention to provide an effective, etiicient and practical load snubber for the end of a boom member for stabilizing loads on the boom and thereby preventing pendulation of the load and providing precise control of the load. Other objects and advantages of the present invention will become ice more apparent in the description of the preferred embodiments set forth below.

Brief description of the drawings FIG. 1 is a side elevation of an embodiment of the present invention with portions broken away to expose interior structure.

FIG. 2 is an end view in elevation of an embodiment shown in FIG. 1.

FIG. 3 is a side elevation in section taken along the line 33 in FIG. 2.

FIG. 4 is an end elevation in section taken along the line 4-4 in FIG. 3.

FIG. 5 is a plane view in section taken along the line 5-5 in FIG. 1.

FIG. 6 is a side elevation in section taken along the line 6-6 in FIG. 7, showing an alternative embodiment of the present invention.

FIG. 7 is an end elevation of the embodiment shown in FIG. 6 with portions broken away to illustrate interior structure.

FIG. 8 is a side elevation of a portion of a third embodiment of the invention.

FIG. 9 is an end elevation in section of the third embodiment taken along the line 9@ in FIG. 8.

Description of the preferred embodiments The embodiments disclosed here are intended for use with the crane shown in the copending application of the same inventor owned by the same assignee, entitled Articulated Crane lib, Ser. No. 628,934, filed on Apr. 6, 1967.

That application discloses a marine crane mounted on an oceanographic survey vessel for hoisting exploratory submarines, launches, buoys and the like to, and from the sea. The crane itself is an hydraulic crane with a cantilevered telescoping boom, and it has its main hoist apparatus mounted on a jib that is pivotally suspended from the foot section of the boom. An auxiliary hoist mechanism is mounted in the conventional way on the foot of the boom with the auxiliary hoist cable extending over hoist sheaves on the top of the boom. The load snubber shown in the drawing is mounted on the end of the articulated jib 1, so that when the boom (not shown) extends horizontally over the side or end of the vessel (not shown) and the articulated jib is suspended vertically, the end of the jib 1 will be a short distance above the water level. A hoist line 2 with a book 3 secured on its end extends from an hydraulically driven main hoist drum (not shown), which is also mounted on the jib 1, between a pair of sheaves 4 and 5' that support and guide it. Since the utility of a structure embodying the present invention is not confined to an articulated jib 1, as shown in the mentioned copending application, the jib 1 may be referred to as a boom member to indicate a more generic application covering booms, jibs, spars or any other such relatively rigid beam, regardless of its semantic designation.

A framework 6 is Welded to sheave bearings 7 and 8 to support a relatively stationary, brake drum 9 on the top or end of the jib 1. The brake drum is made up of brake segments 10 and 11 that have convex. arcuate profiles and concave arcuate cross sections, and that are mounted on hubs 12 which are supported by the framework 6. These arcuate brake drum segments 10 and 11 make up the brake drum 9 and are mounted parallel to each other on opposite sides of the sheaves 4 and 5 so that the hoist cable 2 with its hook 3 may pass between the arcuate brake drum segments 1i) and 11.

In the embodiments shown here, a brake shoe assembly 14 is mounted on a load 15, which may be a submarine, launch, buoy or some other vessel. The brake shoe 14 is made up of a pair of brake shoe sub-assemblies 16 and 17 mounted parallel to each other and spaced apart with a hook eye 18 between them to be engaged by the hoist book 3. The brake shoe sub-assemblies 16 and 17 are welded to a circular base plate 19, and the hook eye 18 is made up of a pair of side plates 20 and 21 welded to the opposing inside surfaces of the brake shoe sub-assemblies 16 and 17 and to the base plate 19 with a hook bar 22 spanning the side plates 20 and 21 to engage the hook 3. Each of the brake shoe sub-assemblies 16 and 17 are made up of three major pieces. Each has a vertically reciprocal brake shoe chassis 23 and 24 supporting arcuate brake surfaces 25 and 26. The arcuate brake surfaces 25 and 26 have convex profiles and concave cross sections to mate with the arcuate brake drum segments 10 and 11. Pairs of spring sockets 27 and 28, 29 and 30 open downwardly from opposite ends of the respective brake shoe chassis 23 and 24. Channel-shaped projections 33 and 34 extend downwardly from the center of each of the brake shoe chassis 23 and 24 between the pairs of spring sockets 27 and 28, 29 and 38, respectively.

Beneath the shoe chassis 23 and 24 are standards 35 and 36, respectively, making up the second major piece of the brake shoe sub-assemblies 16 and 17. Each of the standards 35 and 36 has a pair of tubular spring seats 37 and 38, 39 and 40, one at each end thereof aligned with the respective spring sockets 27, 28, 29, and 30 in the shoe chassis 23 and 24 immediately above it. The tubular spring seats 37, 38, 33 and 40, and between them are channel-shaped guideways 41 and 42, respectively, to slidably receive the projections 33 and 34 on the brake shoe chassis 23 and 24. The guideways 41 and 42 are welded to the base plate 19 and to the respective tubular spring seats 37, 38, 39 and 40. Between the side plates 20 and 21 of the hook eye 18, which are welded to the standards 35 and 36, respectively, of the brake shoe sub-assemblies 16 and 17 inside the guideways 41 and 42, a hook abutment 43 is welded in place immediately beneath the hook bar 22.

The third set of major components of the brake shoe sub-assemblies 16 and 17 are pairs of preloaded, open spiral, compression springs 44, 45, 46 and 47 which have their upper ends secured in the spring sockets 27, 28, 29 and 30, respectively, and their bottom ends seated in the respective spring seats 37-40 of the standards 35 and 36. Thus, the brake shoe surfaces 25 and 26 are resiliently supported. To support the standards 35 and 36 their vertical position faces buttresses 48, 49, 50 and 51 and have their base edges welded to the base plate 19 and their vertical sections welded to the sides of the tubular spring seats 37, 38, 39 and 40.

The mounting of the hook bar 22 is important, not only for the obvious reason that it supports the load 15 on the hook 3, but also because it is employed to preload the compression springs 44, 45, 46 and 47, and because it performs an essential function in a frictional shock absorber used to dampen any oscillations which might tend to develop in the preloaded springs 44, 45, 46 and 47. The hook bar 22 is mounted through holes 52 and 53 in the side plates 20 and 21, respectively, and the ends of a hook bar 22 further project through slots 54 and 55, respectively, through the guide projections 33 and 34 of the respective brake shoe sub-assemblies 16 and 17. Friction plates 56 and 57 are mounted on the hook bar 22 on the outsides of the guide projections 33 and 34, and the friction plates 56 and 57 have friction linings 58 and 59, respectively, bearing against the outside surfaces of the guide projections 33 and 34. Similarly, the inside surfaces of the channel-shaped guideways 41 and 42 in the standards 35 and 36 also have friction linings 60 and 61 bearing against the inside surfaces of the guide projections 33 and 34. Compression springs 62 and 63 are mounted about the ends of the hook bar 22 and loaded between the respective friction plates 56 and 57 and washers 64 and 65 mounted on the hook bar 22. On one end, an hexagonal head 66 on the hook bar 22 holds the washer 64 against the brake spring 62 and on the other end, a pair of hex nuts 67 are screwed onto the hook bar 22 to hold a washer 65 in place and to load the springs 62 and 63.

The hubs 12 and 13 for the arcuate brake drum surfaces 10 and 11 have inwardly extending ridges 68 and 69 formed on either side of the hoist cable 2 to serve as guides for the hoist cable 2. The hook 3 also has a conventional safety latch 70 on it to prevent its being accidentally disengaged from the hook eye 18. Troughs may also be formed to project from the ends of the brake shoe assembly 14 between the brake shoe sub-assemblies 16 and 17 to receive the hook 3 as it is being lowered and to guide it between the shoe sub-assemblies 16 and 17 to the hook eye 18.

A second embodiment of the invention is illustrated in FIGS. 6 and 7. The second embodiment of the invention is adapted for use with a symmetrical self-engaging hook of the type disclosed and claimed in the copending application of the same inventor and owned by the same assignee, entitled Hoist Line Hook, filed on Apr. 10, 1967, and having the Ser. No. 629,612. An upwardly opening tubular socket 71 is welded to a base plate 72 which is mounted on the load 15. The tubular socket 71 has a flared entrance 73 at its top end leading to a hollow interior 74 with an annular latching groove 75 formed in the interior walls just beneath the flared opening 73. The tubular socket 71 is designed to receive a symmetrical hook 76 which has a tapered shank portion 77 at the top to receive the hoist cable 2 in its center. The shank portion 77 widens into a cylindrical central portion 78 that has outwardly opening slots 79 and 80 formed in its sides to mount steel latch bars 8-1 and 82 pivotally near the bottom ends, so that the top ends of the latch bars 81 and 82 may be biased outwardly by springs 83, one of which is shown. Although only two latch bars 81 and 82 are shown, three are actually used, the third latch bar not being visible in the drawing. A conical side wall 84 begins at the end of the cylindrical central portion 78 and tapers to a gently pointed nose 84 at the bottom of the hook 76 which has a resilient, rubber-like bumper mounted in it. The symmetrical hook 76 has circular cross sections throughout its length and it is supported from the center of this circular cross section, although the cross section might be any substantially symmetrical shape, such as an elliptical shape or a polygonal shape. When the hook 76 is dropped into the tubular socket 71, the steel latch bars 81 and 82 are held in the slots 79 and 80 in the center portion 78 by the walls of the socket 71, until the tops of the latch bars 81 and 82 reach the annular groove 75, when the spring 83 drives the tops of the latch bars 81 and 82 into the groove 75 so as to latch the hook 76 inside the tubular socket 71.

The structure of the brake durm 9 on the end of the jib 1 is the same as in the first embodiment, so no further description of it is required here. However, in the second embodiment, there is a brake shoe assembly 85 made up of two, parallel, brake shoe sub-assemblies 86 and 87 mounted on opposite sides of the tubular socket 71, with portions of the walls of the flared opening 73 cut away to accommodate them. Each of the brake shoe sub-assemblies 86 and 87 is made up of arcuate brake surfaces 8-8 and 89, respectively, mounted on a chassis 90 and 91, which has vertical guide projections 92 and 93, respectively, extending downwardly from its center. The chassis 90 and 91 have downwardly opening spring sockets 94, 95 and 96 beneath the opposite ends of the arcuate brake surfaces 88 and 89. The guide projections 92 and 93 have vertical slots 97 cut in them to slidably receive restraining pins 98 and 99, respectively.

Brake shoe standards 100 and 101 are welded to opposite sides of the tubular socket 71. Each of the brake shoe standards 100 and 101 is made up of tubular spring seats 102, 103 and 104, respectively, mounted vertically on opposite ends of the respective standards 100 and 101. A connecting plate 105 and 106 spans the pairs of tubular spring seats 102, 103 and 104 in each of the standards 100 and 101 and is bolted over a frame member that joins the pairs of tubular spring seats 102, 103 and 104 inside of and spaced from the connecting plate 105. A guideway 113 is formed between the connecting plates 105 and 106 and the adjacent frame member to slidably receive each of the respective guide projections 92 and 93. Compression springs 107, 108 and 109 are mounted in the tubular spring seats 102, 103 and 104, respectively, so that the top ends of the springs 107-109 are mounted in the aligned spring sockets 94, 95 and 96. The compression springs 107-109 are preloaded, by the restraining pins 98 and 99 mounted through holes 110 and 111 in the connecting plates 105 and 106, respectively, and in mating holes 112 in the frame member and through slots 97 in the guide projections 92 and 93 between the respective connecting plates 105 and 106 and frame members.

A third embodiment of the invention is shown in its essential portions in FIGS. 8 and 9 with the undertauding that the remaining structure is identical to that shown in the second embodiment. In the third embodiment, a guide projection 114 in the guideway 113 is a separate member from a hub 115 supporting an arcuate brake surface 116. Although only one brake shoe sub-assembly 117 is shown, it is to be understood that as in the previous embodiments there are two such brake shoe sub-assemblies 117 mounted side by side to mate with the lined arcuate brake surfaces and 11 of the brake drum segments 9. A pair of lugs 118 and 119 project downwardly from the center of the hub 115 and the tope of the guide projection 114 is fitted between the lugs 118 and 119. A pin 120 is loosely fitted through holes in the lugs 118 and 119 and a hole in the tope of the guide projection 114 to effect a hinge connection between the guide projection 114 and the hub 115 such that the end of the guide projection 114 may abut the underside of the hub 115 to relieve the pin 120 from stress. At opposite ends of the hub 115 spring abutment pins 121 and 122 are mounted in sockets 123 and 124, respectively, so as to be aligned with the compres sion springs 107 and 108 mounted in the brake shoe standard 100. Mushroom top pins 125 and 126 are inserted in the tops of the compression springs 107 and 108 to maintain the alignment of the springs 107 and 108 and to abut the aligned spring abutment pins 121 and 122.

The operation of the various embodiments of the pres ent invention is substantially the same, and therefore they can be described together as one, utilizing the appropriate different reference numerals to designate the corresponding different parts in the various embodiments, where applicable. The crane operator first lowers the hook 3, until it engages the hook eye 18 (in the first embodiment) or the tubular socket 71 (in the second embodiment). Having engaged the hooks 3, 76 the operator then hoists the load until the brake shoe assembly 14, 85, 117 engages the brake drum 9, by mating the arcuate brake surfaces and 26, 88 and 89, 116 of the brake shoe subassemblies 15 and 16, 86 and 87, 117 for the arcuate brake drum segments 10 and 11. The crane operator will then continue to draw in the hoist line 2 gradually forcing the brake shoe assembly 14, 85, 117 into tighter engagement with the brake drum 9 and further loading the compression springs 44-47, 107-109. However, the operator will cease to draw in on the hoist cable 2 before the compression springs 44-47, 107-109 are completely compressed. The frictional engagement of the brake shoe assembly 14, 85, 117 with the brake drum 9 will dampen any pendulation of the load in planes approximately parallel to the arc of the brake drum 9. The pendulation approximately transversely of the arc of the brake drum 9 will be dampened by the force of the loaded compression springs 44 47, 107-109 acting upon the spaced apart brake shoe assemblies 16 and 17, 86 and 89, 117. Any oscillation which might tend to be developed in the compression springs 4447 in the first embodiment will be dampened by the frictional shock absorbers in the form of the friction plates 56 and 57 spring biased against the guide projections 33 and 34 the channel-shaped guideways 41 and 42 by the springs 62 and 63. The hinge mounting of the hub in the third embodiment allows the brake lining 116 to adjust itself so as to seat automatically in the drum segment 11 of the brake drum 9.

The foregoing description of the three embodiments of the present invention illustrates a few of the vast number of variations, modifications and alternate structures that may be employed and combined in practicing the present invention. A study of those three embodiments will suggest to persons skilled in the art numerous other embodiments of the invention containing variations specifically adapting the invention to the needs of different applications. For example, it will be readily evident to persons skilled in the art that both the brake shoe and the brake drum may be mounted on the end of the jib 1 and the hook allowed to pass through both of them so as to engage the load and draw it against the brake shoe assembly so as to force the brake surfaces together. It has been convenient in the embodiments shown to employ pairs of brake shoes sub-assemblies mating with pairs of brake drum segments, but it is abundantly apparent to persons skilled in the art that any convenient number of brake shoe sub-assemblies engaging corresponding brake drum segments may be as well employed to practice the present invention. Two different types of hooks have been shown with appropriate hookeye and socket, respectively, to illustrate that the invention is not limited to any specific hookeye and socket or hook and eye arrangement. Having disclosed a frictional shock absorber, the foregoing description will teach those skilled in the art with virtually the same clarity that hydraulic and other types of shock absorbers may be substituted for the frictional shock absorbers shown.

Hence, the invention cannot be limited to the specific structure shown here to illustrate but three possible embodiments of the invention. Instead, the following claims, which set forth the essence of the invention, are intended to define the scope of the invention.

I claim:

1. A load snubber for a crane comprising the combination of a boom member having hoist cable guide means on its free end;

a hoist cable supported on said guide means on said boom member and having a hook on its end to engage a load to be hoisted;

a convexly arcuate brake drum mounted on said free end of said boom member;

a concavely arcuate brake shoe assembly to mate with said brake drum and mounted to be between said brake and said load when said load is hoisted toward said free end of said boom member.

2. A load snubber for a crane as set forth in claim 1 wherein said brake shoe assembly has an arcuate brake surface mounted on a chassis, a standard aligned with said chassis, and preloaded spring means separating said hub and said standard.

3. A load snubber for a crane as set forth in claim 2 wherein said hub has a guide projection extending from it to slidably engage a mating guide member on said standard;

a shock absorber is mounted on said hub and said standard to dampen oscillations in said spring means.

4. A load snubber as set forth in claim 3 wherein said guide projection extending from said chassis is hinge connected to a hub supporting said arcuate brake surface.

5. A load snubber as set forth in claim 1 wherein said brake drum has two spaced apart arcuate brake drum segments;

said hoist cable passes between said brake drum segments;

and said brake shoe assembly has two spaced apart brake shoe sub-assemblies with arcuate brake surfaces to engage said arcuate brake drum segments.

6. A load snubber as set forth in claim 5 wherein said brake shoe assembly is mounted on said load to be hoisted;

and a hook eye is mounted between said brake shoe sub-assemblies to be engaged by said hook on said hoist cable.

7. A load snubber as set forth in claim 5 wherein an upward opening tubular hook socket is mounted on said load to be hoisted;

and said brake shoe sub-assemblies are mounted on opposite sides of said hook socket.

References Cited UNITED STATES PATENTS 2,805,781 9/1957 Senn 21258.1 2,916,162 12/1959 Gercke 212-58.1 3,107,791 10/1963 Michael 212-58.1

10 EVON C. BLUNK, Primary Examiner.

H. C. HORNSBY, Assistant Examiner. 

